Treatment of synthetic linear polycondensation products



Nov. 19, 1963 J. VAN BERGEIJK ETAL 3, 7

TREATMENT OF SYNTHETIC LINEAR POLYCONDENSATION PRODUCTS Filed Nov. 10, 1961 INVENTOR. JAN VAN BERGE Id K WI LLEM BAKKER BY m AT ORN United States Patent Ofiice 3-,l l 1,35? Patented Nov. 19, 1963 3,111,367 TREATMENT OF SYNTHETIC LENEAR PQLYCONDENSATION PRODUCTS Jan van Bergeijk, Arnhem, and Willem Baltker, Velp, Gelderland, Netherlands, assignors to American Enira Corporation, Enka, N.C., a corporation of Delaware Filed Nov. 10, 196i, Ser. No. 151,483 Claims priority, application Netherlands Nov. 18, 196i) 2 Claims. (Cl. 18-54) This invention relates generally to a process for the manufacture of artificial threads, yarns and fibers from synthetic linear polycondensation products and more particularly to a melt spinning method wherein freshly spun threads are wetted, wound into package form, and thereafter drawn.

In carrying out this known process, the yarn sometimes cannot be unwound satisfactorily from the thread packages formed between spinning and drawing because of the many faults produced. This drawback is encountered particularly in cases where the threads were spun and initially wound at a rate of 1,100 meters per minute or higher, and the same difficulty is sometimes experienced in the summer months when air conditions in the drawtwisting department cannot be maintained sufficiently constant.

It has now been found that the aforesaid disadvantage is not encountered if the yarn packages formed on the spinning machines are withdrawn from the influence of the prevailing atmosphere preferably immediately after they have been produced.

It is therefore the object of this invention to provide a process for treating synthetic linear polycondensation products, particularly melt spun threads scheduled for drawing or drawtwisting, which will substantially reduce thread faults produced during unwinding of the initial package and which will provide an equilibrium moisture condition in the package of freshly spun yarn.

The present invention therefore comprises transferring freshly produced yarn packages into an air-tight and substantially sealed envelope, after which the yarn is unwound and subsequently drawn on a drawtwisting machine while maintaining the substantially sealed relationship to protect the spinning bobbins from the atmosphere outside the envelope. It will be understood that neither unconditioned nor conditioned air will have significant access to the spinning bobbins. Nor will conditioned air pass through the envelopes.

Whether drawing yarn or threads which have been spun, moistured and initially collected at a rate of 1,100 meters per minute or higher, or whether drawing in an area having irregular and fluctuating air conditions, it has been found that uniform unwinding from the initial package can be obtained by practicing this invention. Similar improved results can be obtained even after storing of the freshly spun yarn, if during storing and subsequent drawing or drawtwisting the supply package is maintained enclosed from the ambient atmosphere. In drawtwisting it has been found that air conditioning of the drawtwisting area is less essential than conditioning of the package. In other words, a poorly distributed package moisture content produces unsatisfactory unwinding which influences the quality of the thread or yarn more unfavorably than do the relative humidity and temperature of the drawtwisting area. This observation permits utilization of the present invention with less attention being directed to correct conditioning of the drawtwisting department, which means a considerable saving in cost.

The process according to the invention may be carried out in various ways. The spinning bobbins or packages may be wrapped in an envelope after the initial winding operation and may subsequently, at the start of the drawing process, be transferred from the above-mentioned envelope to a container mounted on the drawtwisting machine. The container may then be closed off, leaving an opening for feeding thread to be drawn. The envelope may be formed from polyethylene or any other suitable material.

While the container may be constructed so that it will house either a series or a single supply bobbin, it is preferred that each bobbin be placed in a separate container as soon as it has been filled. The container serves to store the spinning bobbin during the period between spinning and drawing, as well as during the drawing operation. While the bobbin is in the container, the moisture content in the thread and that of the air in the container will reach equilibrium. This equilibrium has been found of particular importance for the satisfactory unwinding of thread from the spinning bobbin.

In order to prevent this equilibrium from being disturbed by the outside atmosphere during storage and transport of the yarn packages, it is recommended that the thread discharge opening of the containers be kept closed. If the thread discharge opening is properly dimensioned, correct atmospheric conditions are maintained in the holder even during the unwinding of the thread from the spinning bobbin. In this connection, it is preferred that the thread be discharged from the container through an opening in the form of a thread guiding eyelet. Even when the humidity in the drawtwisting area deviates considerably, the variation in the degree of humidity inside the container is kept within permissible limits.

It should be noted that the wetting of the freshly spun threads in combination with the usual conditioning of the spinning department leads to a moisture content of the threads which is lower than the moisture content finally desired, although a higher moisture content may be obtained by increasing the relative humidity in the drawtwisting area. The lack of equilibrium between the moisture content of the threads after the winding operation and that of the air in the drawtwisting department leads to adsorption of moisture and consequently to lengthening of the freshly spun threads. The latter phenomenon gives rise to deformation of the yarn pack ages, which may affect the unwinding thereof unfavorably. This package deformation is particularly experienced if the threads have been spun and wound at a very high rate with some degree of pro-orientation or drawing. Pre-orientation apparently causes the yarn to have a relatively high moisture adsorption capacity. As a result, the thread shows a relatively high tendency to adsorb moisture. The degree of moisture adsorption is also furthered if the moisture contents of the threads and of the air in the drawtwisting area vary significantly.

The envelope according to the invention prevents, at least to a considerable extent, the access of moisture to the yarn package before it is unwound in the drawtwisting operation. In this respect, the process difiers from known knitting processes in which yarn rolls are housed in boxes wherein a high relative humidity is maintained. It would be impossible to unwind such a package consisting of threads obtained from synthetic linear polycondensation products.

It is also known in the manufacture of stretched cellulose acetate products to store freshly spun threads in a container after being wound onto a bobbin, and during stretching to unwind from said packages while maintaining the same in the container. In this process the idea is to prevent the solvent still present in the threads from nonuniforrnly evaporating therefrom prior to the stretching operation. This process provides no assistance, however, in the manufacturing and drawing of threads which have been spun without use of volatile solvents.

For further elucidating the present invention, attention is now directed to the accompanying drawings, wherein:

FIGURE 1 shows in elevation an apparatus capable of per-forming the process of this invention; and

FIGURE 2 shows, on an enlarged scale and in section, the preferred conditioning box of this invention.

In FIGURE 1 the numeral 1 refers to a drawtwisting machine of the usual construction. This machine comprises a supporting beam 2 to which a twisting device 3 is secured in the usual manner. Each twisting device consists of a ring 4 which may be reciprocated by means of an appropriate traversing device (not shown in the drawing), a traveler 5 which is slidably mounted on ring 4, a spindle on which a tube 6 is non-rotatahly mounted, and the usual top eyelet 7. The spindle may be rotated by means of a driving belt, also not shown.

A yarn-drawing mechanism is provided immediately above the twisting device 3. This mechanism consists in the first place of a feed roller 8 driven by a motor (not shown). In order to prevent slippage of thread 9, which is fed from a supply bobbin 11, a pressure roller 12 cooperates with feed roller 8, as shown. The surface of this pressure roller 12 is clad with an elastic material, e.g. cork, and the roller is pivotally supported for free rotation by arms 13 (only one shown). With the aid of a thread guide 14, the thread 9 is urged into contact with the pressure roller at an angle of more than 180. In order to prevent incision of the rollers, guide 14 is traversed slowly in the longitudinal direction of the pressure roller 12.

Below the feed roller 8 are mounted two adjacent draw pins 15 around which thread 9 is guided so as to be in contact with each pin at an angle of wrap of about 90. Between the pins 15 and the twisting device 3 there is provided a draw godet 16 which is driven (by a motor not shown) at a surface speed a few times greater than that of the feed roller 8. Near this draw godet 16 is a freely rotatable separator roller 17 which is so positioned that its center line crosses the axis of the draw godet 16 at a small angle in order that the wraps around the draw godet 16 may be kept spaced.

In using the drawtwisting machine described, the supply bobbin 11 is placed in a box or container 18. This container 18 is closed by means of a conical lid 19 in the top of which there is an opening forming thread guiding eyelet 20. The conditioning box 18 and the conical lid are so dimensioned that the thread can be readily drawn off overhead from the supply bobbin 11.

Guiding disc 21 on the supply bobbin provides additional assistance during unwinding. This disc is secured to a cylindrical core 24 fastened to the bottom 23 of the box 18 by means of clamp 22. The core also serves to center the supply bobbin 11 within the container.

Example The above-described apparatus was used to draw an artificial monofilament yarn obtained by extruding polyamino caproic acid having a specific viscosity of 1.12 at 260270 C. into a blowbox in which for a distance of 150 cm. cooling air was blown onto the freshly spun thread at a rate of 800 liters per minute. After the thread was discharged from the blowbox, it was impregnated with an aqueous emulsion of a finishing agent applied by a slowly rotating roller, the underside of which was immersed in the finishing emulsion. The finished thread was wound at a rate of about 1,300 meters per minute. The relative humidity of the winding space was 40%, and the temperature therein was 20 C. The spinning bobbins thus filled were immediately placed in the above-described box 18 and the thread guiding eyelet 20 was closed.

After some hours had elapsed, the box 18 was placed on a drawtwisting machine 1 of the above-described con struction and the thread guiding eyelet 20 was opened. Thereafter the end of the thread 9 was passed around the pressure roller 12, the supply roller 8, and the draw pins 15 in the same manner as indicated in FIGURE 1, after which the thread end was secured to the tube 6 of the twisting spindle 3. After the twisting spindle 3 had been placed in operation, the thread 9 was wrapped a few turns around the draw godet 16 and the guide roller 17 and the drawing process was started. The thread was drawn to 3.12 times its original length at a rate of 380 meters per minute. The relative humidity in the drawtwisting area was and the temperature was 20 C.

The drawn yarn was 15.3 denier. Per 500 gnam-package of twisted yarn the mean number of faults was 0.18. If, on the other hand, the package of undrawn yarn was processed without using the box 18, but under otherwise equal conditions, then the mean number of faults per 500 gram-package of drawn yarn was 0.42.

Since various modifications will become apparent to those skilled in this art, it is intended that the present invention be limited in scope only to the extent set forth in the following claims.

What is claimed is: p

'1. A process for treating synthetic linear polycondensation products which comprises melt extruding said products in the form of yarn, applying a finishing agent to the surface of said yarn prior to collection, collecting said freshly spun and finished yarn in package form, transferring the package of freshly spun and finished yarn to an envelope for maintaining the same sealed against the ambient atmosphere, and subsequently withdrawing the yarn from said package while substantially maintaining the sealed relationship and orienting the same to produce a high strength funicular structure having uniform properties.

2. A process for producing yarns from synthetic linear polycondensation products comprising melt extruding said products in the form of a tow, applying a finishing agent to the surface of said tow prior to collection, collecting said freshly spun and finished tow in package form, thereafter placing the package of freshly spun and finished tow in an envelope for maintaining same sealed against the ambient atmosphere, subsequently transferring said package to another envelope for maintaining said package substantially sealed from the ambient atmosphere during further processing, and thereafter withdrawing the tow from said package while substantially maintaining the sealed relationship and orienting and twisting the same to produce a high strength yarn having uniform properties.

References Cited in the file of this patent Polymers and Resins by Golding, page 288, FIGS. 8-9; published in 1959 by D. Van Nostrand Co., Inc., NY. 

1. A PROCESS FOR TREATING SYNTHETIC LINER POLYCONDENSATION PRODUCTS WHICH COMPRISES MELT EXTRUDING SAID PRODUCTS IN THE FORM OF YARN, APPLYING A FINISHING AGENT TO THE SURFACE OF SAID YARN PRIOR TO COLLECTION, COLLECINT SAID FRESHLY SPUN AND FINISHED YARN IN PACKAGE FORM, TRANSFERRING THE PACKAGE OF FRESHLY SPUN AND FINISHED YARN TO AN ENVELOPE FOR MAINTAINING THE SAME SEALED AGAINST THE AMBIENT ATMOSPHERE, AND SUBSEQUENTLY WITHDRAWING THE YARN FROM SAID PACKAGE WHILE SUBSTANTIALLY MAINTAINING THE SEALED RELATIONSHIP AND ORIENTING THE SAME TO PRODUCE A HIGH STRENGHT FUNICULAR STRUCUTRE HAVING UNIFORM PROPERTIES. 